The Dell Alienware 17 Laptop Supports up to 4 Drives. (Two 2.5" Solid State Drives or Hard Drives in the Internal Bays and One 2.5" Solid State Drive or Hard Drive in the Optical Drive Bay and One mSATA Solid State Drive in the Internal mSATA Slot) Note: The third 2.5" Drive is optional and is located in the optical Drive bay when Installed. If replacing the optical Drive for the third 2.5" Drive, you will need the Dell optical drive bracket p/n 6CTX5 and the optical bay drive cable p/n R64M2 for installation.